Microcantilever sensors are known to be effective for detecting chemical substances at low levels. They can function in two ways. First microcantilevers function as resonators. In this mode, the microcantilever that is coated with a chemically sensitive material attracts a chemical species of interest. As mass adds to the microcantilever, its resonance frequency changes and the change in frequency can be used to quantify the added mass. Secondly, microcantilevers can be used as stress sensors. In this mode, microcantilevers are coated on one side with a chemically sensitive material to which the chemical species of interest adsorbs. When adsorption occurs it creates a chemical imbalance causing the cantilever to bend or deflect. The degree of microcantilever deflection can be used to quantify the concentration of the chemical species to which the microcantilever has been exposed. The present invention is concerned with microcantilever stress sensors that are used to detect contaminants in fluids. Fluid refers to both liquids and gases.
In addition to high sensitivity, a useful microcantilever sensor has to have chemical selectivity. It must be able to distinguish one chemical species from another. Typically, the materials used to sensitize microcantilever stress sensors can adsorb a variety of chemical species which cause the microcantilever to deflect. When used for detection in complex chemical mixtures it is not possible to determine what chemical has been detected.
There is a need to provide a microcantilever stress sensor for selectively detecting a preselected contaminant in a fluid.
There is also a need to provide a method for using a microcantilever stress sensor to determine the concentration of a contaminant in a fluid. In addition, there is a need to provide an array comprising a plurality of microcantilever stress sensors for detecting preselected contaminants in a fluid and determining their concentrations. Accordingly this invention and its embodiments can satisfy these needs.